Fluid pump or motor structure



June 27, 1967 H. M. PURCELL 3,327,636

FLUID PUMP OR MOTOR STRUCTURE Filed April 30, 1965 INVENTOR. HOWARD M. PURCELL I 2 BY 1 5 I L,Q.Q 51% United States Patent 3,327,636 FLUID PUMP 0R MOTOR STRUCTURE Howard M. Purcell, South Euclid, Ohio, assignor, by mesne assignments, to Ashtabula Bow Socket Company, Ashtabula, Ohio, a corporation of Ohio Filed Apr. 30, 1965, Ser. No. 452,106 11 Claims. (Cl. 103126) This invention relates to pumps and is particularly concerned with gear pumps of the type having an inner gear ring inside a larger outer gear.

Pumps of the nature referred to are known and are widely used because they are relatively effective for being compact and inexpensive to manufacture. Such pumps heretofore, however, have presented certain problems in connection with ultimate reduction of costs therein while at the same time maintaining efficient operation particularly with respect to properly sealing the gears at their end faces.

With the foregoing in mind the present invention has as a primary object the provision of a gear pump of the nature referred to which is quite inexpensive to manufacture but which is highly eflicient in operation.

Another object of this invention is the provision of a gear pump of the nature referred to which has extremely long life and which is sufiiciently inexpensive to form a throwaway item so that no service problems are encountered.

Another object of this invention is .the provision of a small gear pump which can be operated directly from a motor shaft and which is particularly adapted for use in automobiles and the like such as for supplying hydraulic fluid for operating convertible tops and similar hydraulically actuated auxiliaries. Another object of this invention is the provision of a gear pump of the nature referred to which will operate equally well in either direction of rotation.

It is also an object of this invention to provide a gear pump of the nature referred to in combination with a makeup reservoir so that the pump can be connected in closed circuit with fluid motor means actuated thereby and the fluid circuit will remain air free of all times.

These and other objects and advantages of this invention willbecome apparent by reference to the following detailed description and accompanying drawings wherein:

FIGURE 1 is a side view of a pump according to the present invention and a driving electric motor therefor partly broken away;

FIGURE 2 is a sectional view indicated by line 22 on FIGURE 1;

FIGURE 3 is a sectional view indicated by line 3-3 on FIGURE 2;

FIGURE 4 is a sectional view indicated by line 44 on FIGURE 3;

FIGURE 5 is a view looking in at one of the housing parts in which the gear pump rotates; and

FIGURE 6 is a plan view of the housing part looking down on top of FIGURE 5.

Referring to the drawings somewhat more in detail, 10 represents an electric motor having an output shaft 12. The electric motor is supplied by the electric lead 14 and may be a reversible electric motor. Shock absorbing mounting means 16 are provided on the motor base.

A pump according to the present invention is generally indicated at 18 and is secured to one end of motor 10 as by nuts 20 threaded on to the through bolts 22. of the 3,327,636 Patented June 27, 1967 motor. The pump comprises an outer casing part 24 which is preferably pressed from a blank and which casing, as will be seen in FIGURE 2, is generally circular with flat regions 26 uniformly distributed about the periphery.

The casing 24 is adapted for receiving housing means 28 which consists of two identical cup-like plastic members. Teflon for example, which are formed to be closely received within the casing 24.

One housing part is indicated at 30 in FIGURES 5 and 6 wherein it will be seen to comprise the plate 32 for engaging the plate 26 of the casing and while having the rounded corners 34 are being received within the rounded part of the casing. This shaping of the casing and the housing parts accurately locates the housing parts in the casing while preventing rotation of the housing parts.

Each housing part has two notches 36 and 38 formed therein which, When the housing parts are brought together in edge to edge engagement, form port means 40 and 42 through which fluid flows to and from the pump. As shown in FIGURE 2 port 40 could be the inlet port and port 42 the outlet port; but it will be understood that the pump is reversible and can pass fluid through the ports in either direction.

Each housing part 30 has a cylindrical cavity 44 therein and an ofi center hole 46 in the bottom wall. The cylindrical cavity 44, when the two housing parts are placed in edge to edge engagement, define a cylindrical chamber in which the outer internal gear 48 is rotatably received. The bores 46 in the housing parts rotatably receive shaft 50 on which is mounted the inner external gear 52 .that meshes with gear 48, as will best be seen in FIGURE 2.

Both gears 48 and 52 are preferably formed of sintered powdered metal but could be produced in any suitable manner. Gear 52 is advantageously sintered directly on its shaft 50 or is formed integrally therewith, whereby vibration of the inner gear is avoided and cutting of the end plates of the pump is eliminated.

The pump can be constructed with both of gears 48 and 52 of the same axial length and the bottom walls of the housing members 30 will in that case seal the face between the gear teeth at the ends of the gear. I have found, however, that the operation of the pump can be improved by forming gear 48 longer in the axial direction than gear 52 and recessing the ends of gear 48 and setting plastic washers, Teflon for example, in the recesses.

The washers are indicated at 54 in FIGURES 3 and 4 and will be seen to comprise portions 56 by means of which the washers are keyed to the large gear 48 so as to rotate therewith. Each washer has a center hole 58 through which shaft 50 extends and each washer radially extends inwardly far enough to close the ends of the two spaces between the gears. The provision of the washers reduces the friction within the pump and reduces the relative speed between gear 52 and the end plate, reduces cutting of the end plates, and thereby promotes longer life and efiicient operation of the pump.

According to the present invention a novel porting arrangement is provided which takes the form of bores 60 in the outer gear which may extend from the two spaces substantially radially outwardly to the outer periphery of the large gear box 48. These bores, of which there may be one or two or more, if it is necessary to convey all of the fluid from the inlet port into the inside of the large gear and out of the large gear to the outlet port. This porting arrangement has been found to be effective and inexpensive to incorporate in the pump and eliminates the difliculty of forming the usual kidney shaped inlet and outlet ports at the ends of the gears, which many times produce sealing problems.

The housing parts 30 of the housing 28 in which the gears are rotatable are, as mentioned, preferably of Teflon or a suitable slippery plastic material, and the housing parts fit closely on the periphery of the outer gear, closely embrace the end faces of the outer gear' and the faces of the washers 54.

Sealing between the inlet and outlet ports is thus extremely good and the pump operates with an extremely high efliciency due to this extremely effective sealing and furthermore, due to the low friction characteristics of the metal outer gear ring in the Teflon housing and the Teflon washers 54 running in the housing.

In actual tests it has been found that the efficiency of the pump actually increases over a period of time, probably due to the fact that the metal gears tend to run high with the plastic washers 54 and the parts 30 of housing 28 which appear, in effect, to establish a sort of labyrinth sealing arrangement that is effective for preventing fluid leakage .and at the same time the friction within the pump is not increased in any way.

It will be noted that the housing 28 is placed in casing 24 with a resilient rubber-like member 62 on one side between the cup housing and the bottom Wall of casing 24 and with a rubber-like washer 64 on the other side of the housing and with this assembly being fixed in .the easing by the ring member 66 pressed into the open side of the casing preferably welded in place. This makes a sealed unit which, at the same time, is inexpensive enough to form a throw-away item should it become defective.

Ring-like member 66 supports a bushing 68 in which shaft 50 is journalled and includes a sealing ring 70 to seal against leakage from the pump into the motor. The connection of shaft 50 with motor shaft 12 is preferably by way of a coupling 72 which will prevent the transmission of vibration from the motor to the pump and thus enhance the efficiency and life of the pump As will be seen in FIGURE 2 communication with ports 40 and 42 is accomplished quite simply by mounting ifittings 74 and 76 in casing 24 to which pipes or tubing or other conduit means can be connected to place the pump in circuit.

A feature of the present invention is to be found in :the make-up reservoir mounted directly on casing 24. The make-up reservoir may take the form of a length of plastic tubing 78 closed at the top by vented cap 80 and connected at the bottom to fitting 82 as by spring ring 84. Fitting 82 has a bore therethrough communicating with port and the bore has therein a seat member 86 normally closed from the pump side by spring pressed ball 88. The ball 88 is lightly spring biased against spring 86 but will yield to permit fluid to flow from the inside of plastic tube 78 into port 40 at any time that port 40 is the inlet port for the pump and any cavitation occurs in the fluid system. Such cavitation would normally occur first at the inlet side of the pump and the aforementioned reservoir structure is thus ideally located to provide makeup fluid to the fluid system when necessary.

It will be understood that this invention is susceptible to modification in order to adapt it to different usages and conditions and accordingly, it is desired to comprehend such modifications within this invention as may fall within the scope of the appended claims.

What is claimed is:

1. A pump comprising; an outer internally toothed gear, an inner externally toothed gear inside said outer gear eccentric thereto and meshing therewith, non-rotatable housing means fitted over and enclosing said gears, circumferentially spaced ports in said housing means communicating with spaced regions about the periphery of said outer gear, passage means in said outer gear C011]:

municating the periphery thereof with the inside of the outer gear for exchanging fluid between said ports when said gears rotate within said housing means, said housing means comprising a pair of cup shaped members fitted over said gears from opposite sides and meeting in edge to edge relation about the outer gear, a cup-like metal casing in which said housing means is received, and a closure member in the open side of said casing.

2. A pump comprising; an outer internally toothed gear, an inner externally toothed gear inside said outer gear eccentric thereto and meshing therewith, non-rotatable housing means fitted over and enclosing said gears, circumferentially spaced ports in said housing means communicating with spaced regionsabout the periphery of said outer gear, passage means in said outer gear communicating the periphery thereof with the inside of the outer gear for exchanging fluid between said ports when said gear-s rotate with said housing means, said housing means comprising a pair of cup shaped members fitted over said gears from opposite sides and meeting in edge to edge relation about the outer gear, a cup-like metal casing in which said housing means is received, a closure member in the open side of said casing, and a rubberlike cushion in the casing on opposite sides of said housing means.

3. A pump comprising; an outer internally toothed gear, an inner externally toothed gear inside said outer gear eccentric thereto and meshing therewith, non-rotatable housing means fitted over and enclosing said gears, circumferentially spaced ports in said housing means communicating with spaced regions about the periphery of said outer gear, passage means in said outer gear c-ommunicating the periphery thereof with the inside of the outer gear for exchanging fluid between said ports when said gears rotate with said housing means, said housing means comprising a pair of cup shaped members fitted over said gears from opposite sides and meeting in edge to edge relation about the outer gear, a cup-like metal casing in which said housing means is received, a closure memher in the open side of said casing, a rubber-like cushion in the casing on opposite sides of said housing means, a bearing in said closure member, and a shaft journaled in said bearing and drivingly connected to saidinner gear.

4. A pump comprising; an outer internally toothed gear, an inner externally toothed gear inside said outer gear eccentric thereto and meshing therewith, non-rotatable housing means fitted over and enclosing said gears, circumferentially spaced ports in said housing means communicating with spaced regions about the periphery of said outer gear, passage meansin said outer gear communicating the periphery thereof with the inside of the .outer gear for exchanging fluid between said ports when; said gears rotate with said housing means, said housing.

means comprising a pair of cup shaped members fitted over said gears from opposite sides and meeting in edge to edge relation about the outer gear, a cup-like metal casing in which said housing means is received, a closure member in the open side of said casing, a rubber-like cushion in the casing on opposite sides of said housing means,'a bearing in said closure member, and a shaft journaled in said bearing and drivingly connected to said inner gear, said housing means having shaft receiving apertures therein on both sides of said inner gear and said shaft engaging both said apertures.

5. A pump comprising; an outer internally toothed gear, an inner externally toothed gear inside said outer gear eccentric thereto and meshing therewith, non-rotatable housing means fitted over and enclosing said gears, circumferentially spaced ports in said housing means communicating with spaced regions about the periphery of said outer gear, passage means in said outer gear com-- municating the periphery thereof with the inside of the outer gear for exchanging fluid between said ports when said gears rotate with said housing means, said outer gear having a greater width than said inner gear, counterbores in the opposite faces of said outer gear, and washer elements mounted in said counterbores and engaging the end faces of said gears to close the ends of the tooth spaces thereof.

6. A pump comprising; an outer internally toothed gear, an inner externally toothed gear inside said outer gear eccentric thereto and meshing therewith, non-rotatable housing means fitted over and enclosing said gears, circumferentially spaced ports in said housing means communicating with spaced regions about the periphery of said outer gear, passage means in said outer gear communicating the periphery thereof with the inside of the outer gear for exchanging fluid between said ports when said gears rotate with said housing means, said outer gear having a greater width than said inner gear, counterbores in the opposite faces of said outer gear, washer elements non-rotatably mounted in said counterbores and closing the tooth spaces at the ends of said gears, said washers and said housing means being formed of a low friction plastic material.

7. A pump comprising; an outer internally toothed gear, an inner externally toothed gear inside said outer gear eccentric thereto and meshing therewith, non-rotatable housing means fitted over and enclosing said gears, circumferentially spaced ports in said housing means communicating with spaced regions about the periphery of said outer gear, passage means in said outer gear communicating the periphery thereof with the inside of the outer gear for exchanging fluid between said ports when said gears rotate with said housing means, said outer gear having a greater width than said inner gear, counterbores in the opposite faces of said outer gear, washer elements non-rotatably mounted in said counterbores and closing the tooth spaces at the ends of said gears, said washers and said housing means being formed of a low friction plastic material, said housing means being noncircular in cross sectional shape, a cup-like metal casing conforming in shape to said housing means and surrounding said housing means, a closure member fixed in the open side of said casing, resilient elements in the casing on opposite sides of said housing means, and fittings in said casing for connection to fluid conduits and providing communication of the conduits with said ports.

8. A pump comprising; an outer internally toothed gear, an inner externally toothed gear inside said outer gear eccentric thereto and meshing therewith, non-rotatable housing means fitted over and enclosing said gears, circumferentially spaced ports in said housing means communicating with spaced regions about the periphery of said outer gear, passage means in said outer gear communicating the periphery thereof with the inside of the outer gear for exchanging fluid between said ports when said gears rotate with said housing means, said outer gear having a greater width than said inner gear, counterbores in the opposite faces of said outer gear, washer elements non-rotatably mounted in said counterbores and closing the tooth spaces at the ends of said gears, said washers and said housing means being formed of a low friction plastic material, said housing means being noncircular in cross sectional shape, a cup-like metal casing conforming in shape to said housing means and surrounding said housing means, a closure member fixed in the open side of said casing, resilient elements in the casing on opposite sides of said housing means, fittings in said casing for connection to fluid conduits and providing communication of the conduits with said ports, a reservoir mounted on the casing and a connection through the casing leading from said reservoir to one of said ports, and a check valve in said connection opening toward said port.

9. A pump comprising; an outer internally toothed gear, an inner externally toothed gear inside said outer gear eccentric thereto and meshing therewith, non-rotatable housing means fitted over and enclosing said gears,

circumferentially spaced ports in said housing means communicating with spaced regions about the periphery of said outer gear, passage means in said outer gear communicating the periphery thereof with the inside of the outer gear for exchanging fluid between said ports when said gears rotate with said housing means, said outer gear having a greater width than said inner gear, counterbores in the opposite faces of said outer gear, washer elements non-rotatably' mounted in said counterbores and closing the tooth spaces at the ends of said gears, said washers and said housing means being formed of a low friction plastic material, said housing means being noncircular in cross sectional shape, a cup-like metal casing conforming in shape to said housing means and surrounding said housing means, a closure member fixed in the open side of said casing, resilient elements in the casing on opposite sides of said housing means, and fittings in said casing for connection to fluid conduits and providing communication of the conduits with said ports, an additional fitting mounted in said casing having a passage communicating with one of said ports, a check valve in the passage of the additional fitting opening toward said one port, a tube sealed at one end to the additional fitting and communicating with the passage therein for containing make-up fluid, and vented closure means in the other end of said tube.

10. A pump comprising; an outer internally toothed gear, an inner externally toothed gear inside said outer gear eccentric thereto and meshing therewith, nonrotatable housing means fitted over and enclosing said gears, circumferentially spaced ports in said housing means communicating with spaced regions about the periphery of said outer gear, passage means in said outer gear communicating the periphery thereof with the inside of the outer gear for exchanging fluid between said por-ts when said gears rotate with said housing means, said outer gear having a greater width than said inner gear, counterbores in the opposite faces of said outer gear, washer elements non-rotatably mounted in said counterbores and closing the tooth spaces at the ends of said gears, said washers and said housing means being formed of a low friction plastic material, said housing means being non-circular in cross sectional shape, a cuplike metal casing conforming in shape to said housing means and surrounding said housing means, a closure member fixed in the open side of said casing, resilient elements in the casing on opposite sides of said housing means, and fittings in said casing for connection to fluid conduits and providing communication of the conduits with said ports, said casing having a mounting flange at the open end.

11. A pump comprising; an outer internally toothed gear, an inner externally toothed gear inside said outer gear eccentric thereto and meshing therewith, non-rotatable housing means fitted over and enclosing said gears, cireumferentially spaced ports in said housing means communicating with spaced regions about the periphery of said outer gear, passage means in said outer gear communicating the periphery thereof with the inside of the outer gear for exchanging fluid between said ports when said gears rotate with said housing means, said outer gear having a greater width than said inner gear, counterbores in the opposite faces of said outer gear, washer elements non-rotatably mounted in said counterbores and closing the tooth spaces at the, ends of said gears, said washers and said housing means being formed of a low friction plastic material, said housing means being non-circular in cross sectional shape, a cup-like metal casing conforming in shape to said housing means and surrounding said housing means, a closure member fixed in the open side of said casing, resilient elements in the casing on opposite sides of said housing means, and fittings in said casing for connection to fluid conduits and providing communication of the conduits with said ports, said casing having a mounting flange at the open end, an electric 7 8 motor bolted to said flange, and coupling means 'connect- 2,657,638 11/ 1953 English 103-126 ing said shaft with the water output shaft. 2,880,676 4/1959 Succop 103126 3,105,446 10/1963 Blomgran et a1 103-126 U I l z l s z TENTs 5 FOREIGN PATENTS v N TE 3,944 1915 Great Britain.

1,9 9 9 iw 103126 270,000 5/1927 mat Britain, 2x32: 5 182-152 284,411 1/1928 Great Britain.

2619:0411 11/1952 iii .111: 103:126 DONLEY STOCKING Primary Examine- I 2,619,911 12/1952 Svenson 103-126 10 WILBUR J. GOODLIN, Examiner. 

1. A PUMP COMPRISING; AN OUTER INTERNALLY TOOTHED GEAR, AN INNER EXTERNALLY TOOTHED GEAR INSIDE SAID OUTER GEAR ECCENTRIC THERETO AND MESHING THEREWITH, NON-ROTATABLE HOUSING MEANS FITTED OVER AND ENCLOSING SAID GEARS, CIR CUMFERENTIALLY SPACED PORTS IN SAID HOUSING MEANS COMMUNICATING WITH SPACED REGIONS ABOUT THE PERIPHERY OF SAID OUTER GEAR, PASSAGE MEANS IN SAID OUTER GEAR COMMUNICATING THE PERIPHERY THEREOF WITH THE INSIDE OF THE OUTER GEAR FOR EXCHANGING FLUID BETWEEN SAID PORTS WHEN SAID GEARS ROTATE WITHIN SAID HOUSING MEANS, SAID HOUSING MEANS COMPRISING A PAIR OF CUP SHAPED MEMBERS FITTED OVER SAID GEARS FROM OPPOSITE SIDES AND MEETING IN EDGE TO EDGE RELATION ABOUT THE OUTER GEAR, A CUP-LIKE METAL CASING IN WHICH SAID HOUSING MEANS IS RECEIVED, AND A CLOSURE MEMBER IN THE OPEN SIDE OF SAID CASING. 